1. Field of the Invention
The present invention generally relates to a cassette loading apparatus and, more particularly, to a cassette loading apparatus for substantially horizontally conveying a tape cassette used in a magnetic recording/reproducing apparatus such as a video tape recorder (to be referred to as a VTR hereinafter), and loading the cassette in a tape drive unit.
2. Description of the Related Art
In a conventional cassette loading apparatus in a recent VTR, when a tape cassette is substantially horizontally inserted in a cassette holder, a front loading mechanism is operated to convey the cassette holder. When the cassette holder reaches a portion on a tape drive unit, the tape cassette which is moved downward and held is loaded in the tape drive unit. At this time, a cassette lid of the tape cassette is opened, and a tape extraction member of the tape loading mechanism is inserted inside the tape. The tape loading mechanism then performs tape loading.
In an ejection mode, an operation opposite to the above-mentioned loading operation is performed to move the cassette outside the cassette holder, i.e., unloading is performed.
In such a cassette loading apparatus, a demand has arisen for achieving a simple arrangement, highly reliable operation control, and simplification of manufacturing and assembly operations.
To meet the above demand, a drive mechanism for conveying a cassette holder through a worm and a worm wheel, to which a drive force of a drive motor is transmitted through a belt transmission mechanism, is exemplified. More specifically, in the worm and worm wheel, if a front loading mechanism is operated, and an unloading operation of the cassette holder which holds the tape cassette is erroneously and forcibly stopped by a user, a very large torque acts on the worm, and a cling between the worm and the worm wheel or the worm support unit may often occur. In this case, in order to release a cling of the worm, a drive motor is driven in the reverse direction, and the worm is reversed.
In the above-mentioned cassette loading apparatus, however, a very large torque is required to release a cling of the worm, unlike in a drive operation. Therefore, unless a large cassette loading drive motor having a torque larger than a starting torque is used, it is difficult to assure a reliable operation. Therefore, cost and power consumption are undesirably increased. In addition, the worm must be assembled with the worm wheel through a bearing while it is axially supported in the thrust and radial directions. Therefore, the assembly and mounting operations are complicated, and hence cost is further increased.
As described above, in the conventional cassette loading apparatus, due to a worm cling, unless a drive motor having a large drive force is used, it is difficult to assure a reliable operation, and assembly and mounting operations of the worm are complicated, thus causing high cost and high power consumption.